Basic Internet Connectivity And Modem Help

[Clarenancy]

So we have been having intermittent issues with our connection recently. For average browsing it is noticeable but not a huge issue. However, for any continuous connection usage it is a showstopper.

Basically our connection is operating at normal speeds most of the time, but frequently and for short intervals it will drop completely or have huge spikes. And this causes timeouts on basically any continuous connection application (streams, VPN, voice, games, downloads, etc).

*I have set up all links so that they should open in a new window by default*

So I made an IMGUR gallery of some tests I ran today ( http://tarch.imgur.com/all/ ), I will link the images of the test individually with description below.

When I got home I connected to my modem's web interface and did a "/ping -t google.com" and took a screencapture of the results. My modem (brand new SB6121) seems in order:

http://i.imgur.com/X7k3p.png

While I was at work and class I left my computer running with PingPlotter going and here are the results from that. The first one is the overall results (only 30 minute timeline visible on the timeline but all 20404 tests visible on the plot/histogram). The second is with a random (seemingly good portion of the timeline) to show that even where the timeline looks decent it's such a large span of time that spikes are hidden.

http://i.imgur.com/5sBl6.png

http://i.imgur.com/F41tp.png

The last image is a short little 3d traceroute I ran once I got home to assess things from a third perspective. This is screencapture of those results, roughly minute and a half of testing.

http://i.imgur.com/WdOAg.png

So those are examples of the issue. As I stated, the modem seems excellent.

So the first response is probably going to be: "What have you tried?"

- I have bypassed my router, from 3 of my computers and tested the connection independent of any home network from each of those 3 machines. Results were consistent with what is shown above.

- I have bypassed the splitter that separates my coax. Results consistent.

- I have switched out ethernet cables (storebought and home-made). Results consistent.

- I have cycled hardware umpteen times. Results consistent.

- I have tested at different times of day. Results consistent.

- I have renewed my IP address

- I have tried a different modem (hence the brand new SB6121)

- I have inspected my lines and connections and outlets

- I have had many beers. (after I was done with all of the above, never during)

- Oh I called comcast, the guy did a ping test, said it looked great. When I said it wasn't he had me do a speedtest and said those results were great.

So, advice? Thoughts? Help?

I'll update this thread as new things develop (or not since about all I can do is lurk on forums at the moment).

[i-am-nerdburg]

We need more information please:

- Post your upstream and downstream signal levels. Click the link or type: http://192.168.100.1 into your browser. We are interested in your power levels (dBmV) and your Signal to Noise Ratio (SNR). You may also want to contact Comcast and ask for your upstream SNR (uSNR) and receive level.
- Post your modem’s error logs.
- Post the make and model of your modem.
- Post the make and model of your router if you have one.
- Let us know if you contacted Comcast or had a tech visit.
- Let us know what the lights on your modem are doing when you are having problems.

[Clarenancy]

First link ( http://i.imgur.com/X7k3p.png ) containes dSNR (35 <dSNR< 36) and downstream dBmV (-1<dBmV<0) and upstream dBmV (41<dBmV<42). I didn't explicitily ask for my uSNR when I called, but he said my signals all looked good. So I assumed he checked that. Maybe I shouldn't have accepted an implicit answer, but yeah.

As for modem error log: http://i.imgur.com/XQifO.png 

The thing at 2000 I don't know. But the 1700s were me switching out Coax cable for giggles. No effect.

Despite my IT knowledge, "No Ranging response" means little to me.

The lights are always indicative of good connection. On both modems. At the moment (SB6121) uplink/downlink solid blue, online solid green, power solid green, link status flickering orange. For all intents and purposes I'm using the SB6121 at all times for now.

As for the router: Belkin F7D8302 v1 with newest firmware.

And no, I have not had a tech come out. I am not about to pay someone to fix my problem until I have exhausted all possibilities on my end.

Thanks

[i-am-nerdburg]

Your signal power levels are fine, but that doesn't always tell the whole story. You may have an upstream noise issue (you can call Comcast and ask for uSNR and receive level.) Since you swapped the modem and have the same issue with or w/o the router, that pretty much leaves you with a signal problem. Your issues could be caused by bad/substandard wiring/connectors/splitters or it could be a problem on Comcast's end. I don't see a lot of other options for other than calling for a tech.

[Clarenancy]

Yeah, I'm about out of ideas. Going to inspect the wire under the house at some point this weekend. If that doesn't turn anything up, I'll call for a tech. We had some pretty rough weather the day before it started with multiple power outages, but usually they are all over that in this area (southern alabama). With hurricanes we usually have cable up before power.

Thanks again

[taintedbloop]

Clarenancy, where do you live? I'm having the exact same problem, as well as many other users on this forum. I've had 3 techs come out and tell me they cant find the issue. I get these quick 2 second lag spikes that happen mostly in the evening/at night. It started maybe 2-3 weeks ago.

I live in Ft Lauderdale, Florida. What about you?

Edit: Doh, I see you said southern alabama. 

Many users on this forum that I see is having this problem when I ask their location they say the southeastern part of the US. From what I know, all our internet gets routed through a main hub in atlanta. Could this be a widespread issue? It's extremely annoying playing games/skype and such. 

I've replaced my router, modem, cables, splitters, and got a new PC in the meantime and no results. I'm at a loss at this point. It doesn't put an entry in the modem logs, either.

Clarenancy, can you look at your modem logs and see if it registers as any type of error? Thats the whole issue for me - I have no concrete proof because the small lag spike doesnt register as any errors because I never actually fully disconnect.

For a little more info look at these threads with more users with similar problems:

http://forums.comcast.com/t5/Connectivity-and-Modem-Help/Another-Frustrated-Gamer-and-General-Intern...

http://forums.comcast.com/t5/Connectivity-and-Modem-Help/Connection-issues-lag-spikes-particularly-i...

WTH is going on? Why are there not more complaints?

[jjones630]

Hi .. I'm in Chicago .. connection issues worse the past few days .. we did have a pretty bad windstorm here couple days ago .. SB6121 modem resets itself .. or goes down and I have to reset (unplug modem and router .. etc) when I have to physically reset it the blue send light is flashing (upstream signal) .. does that signal come from Comcast ..?  After I do the reset it works ok for a while .. sometimes for as long as 8-10 hours .. sometimes for shorter periods .. frustrating !!  I've called Comcast .. they give the same old instructions .. and claim that everything looks fine with their equipment so it must be mine .. I really can't afford to pay a tech to come out, so I'm trying to fix it on my own .. any help would be much appreciated ..

[Clarenancy]

So the problem has been fixed. When I was on my way to work monday morning there were comcast trucks up and down the street. Since then performance has been good. Guess it was some of the lines. 

As for the other folks. I would suggest doing the things I tried, if you can access them. Bypass any splitters/routers you have. Take the time to do each one of these things one step at a time. Don't elmininate multiple possibilities at once. If bypassing splitter/router don't result in a difference, try the cordage. After that I'd probably call a tech and be insistant that they run long tests if they don't notice anything. 

Best of luck and thanks to all.